Drop unused new_keypair.cpp.

* python-gnupg handles keypair generation now.
Merge pull request #664 from Renelvon/purge_cpp

Drop unused new_keypair.cpp.
Remove GNU LGPL from node/db_store.py
Remove GNU LGPL from node/routingtable.py
Remove GNU LGPL from node/setup_db.py
Remove GNU LGPL from node/datastore.py
Remove GNU LGPL from test/test_dbstore.py
Remove GNU LGPL from db/migrations/*.py